linux-kernel - Re: [PATCH 3/4] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and SR1.1

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Message-ID: <1f424bbd-3830-41f9-af4b-9d17af42edaa@ti.com>
Date: Thu, 7 Aug 2025 12:28:10 -0500
From: Andrew Davis <afd@...com>
To: Judith Mendez <jm@...com>, Nishanth Menon <nm@...com>,
        Tero Kristo
	<kristo@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Adrian Hunter
	<adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
CC: Vignesh Raghavendra <vigneshr@...com>,
        Santosh Shilimkar
	<ssantosh@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH 3/4] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and
 SR1.1

On 8/5/25 6:49 PM, Judith Mendez wrote:
> This adds SDHCI_AM654_QUIRK_DISABLE_HS400 quirk which shall be used
> to disable HS400 support. AM62P SR1.0 and SR1.1 do not support HS400
> due to errata i2458 [0] so disable HS400 for these SoC revisions.
> 
> [0] https://www.ti.com/lit/er/sprz574a/sprz574a.pdf
> Signed-off-by: Judith Mendez <jm@...com>
> ---
>   drivers/mmc/host/sdhci_am654.c | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index e4fc345be7e5..b7d2adff3277 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -156,6 +156,7 @@ struct sdhci_am654_data {
>   
>   #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
>   #define SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA BIT(1)
> +#define SDHCI_AM654_QUIRK_DISABLE_HS400 BIT(2)
>   };
>   
>   struct window {
> @@ -820,6 +821,9 @@ static int sdhci_am654_init(struct sdhci_host *host)
>   	if (ret)
>   		goto err_cleanup_host;
>   
> +	if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_DISABLE_HS400)
> +		host->mmc->caps2 &= ~(MMC_CAP2_HS400 | MMC_CAP2_HS400_ES);
> +
>   	ret = __sdhci_add_host(host);
>   	if (ret)
>   		goto err_cleanup_host;
> @@ -883,6 +887,12 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
>   	return 0;
>   }
>   
> +static const struct soc_device_attribute sdhci_am654_descope_hs400[] = {
> +	{ .family = "AM62PX", .revision = "SR1.0" },
> +	{ .family = "AM62PX", .revision = "SR1.1" },
> +	{ /* sentinel */ }
> +};
> +
>   static const struct of_device_id sdhci_am654_of_match[] = {
>   	{
>   		.compatible = "ti,am654-sdhci-5.1",
> @@ -970,6 +980,12 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>   	if (ret)
>   		return dev_err_probe(dev, ret, "parsing dt failed\n");
>   
> +	soc = soc_device_match(sdhci_am654_descope_hs400);
> +	if (soc) {
> +		dev_err(dev, "Disable descoped HS400 mode for this silicon revision\n");

Not really an error, use dev_info() or dev_warn(). Also this message
should go up in the init function when the caps are actually removed,
and only printed if the caps were set in the first place.

Andrew

> +		sdhci_am654->quirks |= SDHCI_AM654_QUIRK_DISABLE_HS400;
> +	}
> +
>   	host->mmc_host_ops.start_signal_voltage_switch = sdhci_am654_start_signal_voltage_switch;
>   	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>